Compressor with retractable guide vanes

ABSTRACT

In a compressor having a bladed rotor, a system is included for introducing guide vanes into the fluid path leading to such blades, such guide vanes being completely removable from said path when desired.

Umted States Patent 1191 1111 3,861,823 Serovy Jan. 21,1975

1 1 COMPRESSOR WITH RETRACTABLE 3,465,950 9/1969 Freid et a1. 415/121 0GUIDE VANES 3,733,814 5/1973 Hull, Jr. et a 415/121 0 [75] Inventor:George K. Serovy, Ames, Iowa FOREIGN P N R APPLICATIONS 951,944 I 4/1949France 415/147 [73] Ass'gnee' Cate'pma' Tract" 9 1,142,112 3/1957 France415/147 [22] Filed; Jan, 15, 1973 588,895 12/1959 Canada 415/147 702,2661/1954 Great Britain 415/147 [21] Appl. No.: 323,936

Primary Examiner-Henry F. Raduazo [52] US. Cl. 415/147, 415/151 t y, gor FirmPhillips, M [51] Int. Cl. F04d 27/00 i ge pi & St aba [58] Fieldof Search 415/121 G, 147, 151, 150

[57] ABSTRACT [56] References Cited In a compressor having a bladedrotor a system is in- UNITED STATES PATENTS cluded for introducing guidevanes into the fluid path 2,838,227 6/1958 Thomas et al. 415/147 l di tuch blades, such guide vanes being com- 2,858,974 11/1958 Bullock et a1415/147 pletely removable from Said path when dash-L 2,870,956 l/1959Dhonau et a1. 415/147 3,237,563 3/1966 Hartland 415/151 5 Claims, 8Drawing Figures COMPRESSOR WITH RETRACTABLE GUIDE VANES BACKGROUND OFTHE INVENTION This invention relates to compressors, and moreparticularly, to a fluid compressor which incorporates movable inletguide vanes which direct a fluid to the compressing means.

Rotating fluid compressors used with gas turbine engines are normallydesigned to achieve peak efficiency under pre-determined operatingconditions which can be referred to as optimum design conditions. Forinstance, the density of the fluid is dependent upon its temperature andpressure, and changes in either of these parameters will affect thefluid density and consequently the ability of a compressor toefficiently compress the fluid. In addition, changes in output power bythe engine may require a corresponding change in compressor speed. Areduction in compressor speed will decrease the velocity of the inletfluid, thereby producing a higher relative inlet flow angle with respectto the compressor blades. Such a condition contributes to aerodynamiclosses which could produce a phenomenon commonly referred to as bladestall since it corresponds to the well-known performance of an airplanewing disposed at too high an angle of attack.

The use of inlet guide vanes in a turbine compressor to reduce the inletflow angle for operating at a level other than its optimum designcondition is well known to the art. U.S. Pat. No. 2,733,853 to W. E.Trumpler illustrates the use of movable inlet guide vanes. Flexiblevanes capable of varying the blade camber angle are described in US.Pat. No. 3,397,836 to W. C. Badger et al. These approaches, whileimproving the inlet flow angle at part load or at some other conditionless than optimum design condition, are generally not required fornormal operation under conditions at which the compressor is designed tooperate at maximum efficiency. Consequently, even though the vanes areusually paired or otherwise adjusted for zero turning of the inlet fluidat optimum design conditions, the presence of the vanes in the flowstream produces undesirable blockage of the fluid inlet when they arenot required.

SUMMARY OF THE INVENTION It is an object of this invention to provide,in a fluid compressor, a guide vane system which can be called on tofunction only when required.

It is a further object of this invention to provide a guide vane systemwhich properly improves the inlet flow angle of the fluid underconditions other than the optimum design condition.

It is a still further object of this invention to provide a guide vanesystem which, while fulfilling the above objects, includes automaticsensing and control means to properly vary the inlet flow angle of suchfluid.

It is a still further object of this invention to provide a guide vanesystem which, while fulfilling the above objects, is simple andefficient in design.

Broadly stated, the invention is in a compressor having a housing, abladed rotor rotatably associated with the housing, and means definingan annular fluid inlet passage leading into the blades of said rotor andthrough which said fluid passes to said rotor blades. Such inventioncomprises means selectively positionable in said annular fluid inletpassage to redirect a portion of the fluid passing to said rotor bladesthrough said annular fluid inlet passage and completely removable fromsaid annular fluid inlet passage.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects of theinvention will become apparent from a study of the followingspecifications and drawings, in which:

FIG. I is a sectional elevation of a fluid compressor incorporating theinvention;

FIG. 2 is a sectional view taken along the line ll-ll of FIG. 1, andfurther showing control means of the system;

FIG. 3 is an enlarged view of an area of the fluid compressor; and,

FIGS. 48 are vector diagrams representing the fluid flow at the tip andhub portions of the rotor blades of the compressor, under variousoperating conditions.

DESCRIPTION OF THE PREFERRED EMBODIMENT With particular reference toFIGS. 1 and 2, a compressor for a gas turbine engine incorporating theprinciples of the present invention is generally indicated by thereference numeral 10. Such compressor 10 includes a housing 12 made upof a stationary central housing 14 and a stationary outer housingassembly 16. A bladed rotor 18 is rotatably mounted to the centralhousing 14 and is rotatable about its axis. The blades 20 of the rotor18 each define a tip portion 22 and a hub portion 24. The housingassembly 16 comprises a circular shroud portion 26 and a partiallycontoured annular ring 28 joined to the shroud portion 26 by a pluralityof bolts 30. The central housing 14 and housing assembly I6 define anannular fluid inlet passage 32 leading into the blades 20 of the rotor18 and through which fluid passes to said rotor blades 20.

A plurality of guide vanes 34 are associated with the housing 12 asshown. Each guide vane 34 includes a rack member 36, with the guide vane34 fixed thereto. Each rack member 36 is reciprocally mounted in a slot38 in the outer housing assembly 16, so that each guide vane 34 ismovable into the annular fluid inlet passage.

32 toward the axis of rotation of the rotor 18, and outwardly therefromto be completely removed from the annular fluid inlet passage 32.Further included are a plurality of pinion gears 40, each pinion gear 40being rotatably mounted to the other housing assembly 16, between shroudportion 26 and annular ring 28, with the teeth thereof in an engagementwith teeth of a rack member 36.

A ring gear 42 is rotatably mounted to housing assembly 16 on a bushing44. Bushing 44 is supported on the annular ring 28 to provide a pilotingand bearing surface for the ring gear 42. Each pinion gear 40 has theteeth thereof in engagement with the teeth of the ring gear 42. It willbe seen that rotation of the ring gear 42 in one direction relative tothe housing 12 rotates the pinion gears 40 to move the rack members 36and guide vanes 34 attached thereto inwardly of the annular fluidpassage 32, and rotation of the ring gear 42 relative to the housing 12in the other direction rotates the pinion gears 40 to move the rackmembers 36 and guide vanes 34 attached thereto outwardly of the annularfluid inlet passage 32.

For the purpose of illustrating the operation of the present invention,an imaginary vertical plane A-A positioned immediately upstream of thecompressor rotor 18, as indicated in FIG. 3 by broken lines, is used asa reference plane with regard to the ensuing discussion of inlet flowvelocity distribution. Although the vectors in FIGS. 4-8 are not drawnto a particular scale, conventional vector notations familiar to thoseskilled in the art are used.

FlGS. 4 and 5 illustrate typical vector diagrams representing the flowat the rotor blade tip and hub portions 22,24, respectively, foroperation at the optimum design conditions. The absolute velocity vectoris perpendicular to the rotor 18 velocity vector U. The velocity of theinlet flow relative to the rotor 18 is represented by vector V, and theincluded angle between the vectors V and V, designated Beta, representsthe relative inlet flow angle of the fluid. It should be noted that theabsolute velocity vector V is essentially equal at the tip 22 and hub 24portions. The rotor 18 velocity U, however, is a function of the rotor18 radius, and is therefore greater at the tip 22 than at the hub 24.Thus, the relative inlet flow angle Beta of FIG. 4 is likewise greaterat the tip 22 than the flow angle Beta of FIG. 5 at the hub 24. Thiscondition is anticipated and the rotor blades 20 are normally designedwith the appropriate incidence angle at the tip 22 and hub 24 portionsto compensate for differences to the relative inlet flow angle foroperation at a predetermined optimum design condition.

Since the rotor velocity U is greater at the tip 22 than at the hub 24portion, the tip 22 is influenced more than the hub 24 by changes inrotor 18 velocity. For example, FIG. 6 represents a velocitydistribution diagram for inlet flow at the tip 22 that is typical ofoperation at slightly less than the optimum design condition. Theabsolute velocity vector V has decreased proportionately more than therotor 18 velocity vector U, and is slightly lower than at the optimumdesign condition, and therefore the relative inlet flow angle Beta isgreater than for the predetermined optimum design condition. Theincrease in the relative inlet flow angle Beta contributes to losses atthe tip 22, thus lowering the compressor 10 efficiency. Insertion of aguide vane 24 partially into the inlet passage 32 deflects or redirectsa portion of a fluid passing through the passage 32 to the tip portions22 of the rotor blades 20, thereby altering the relative inlet flowangle Beta and the relative velocity Vector V as indicated by a solidvector in the diagram.

At operating conditions which deviate more greatly from the optimumdesign condition, both tip 22 and hub 24 portions will show significantchanges in the relative inlet flow angle Beta. This condition isrepresented by broken vectors in the velocity diagrams of FIGS. 7 and 8.Insertion of the inlet guide vanes across the inlet passage to redirectthe inlet flow to both the tip portions and hub portions of the rotorblades, as represented by solid vectors, effectively reduces therelative inlet flow angle Beta to values near that of normal optimumdesign condition operation.

The principal control elements are shown schematically in FIG. 2. Ahydraulic cylinder 50 is anchored at one end 52 to a compressor framemember 54. The hydraulic cylinder 50 includes a piston 56 which isattached to a tab 58 of the ring gear 42 by a control rod 60. A controlunit 62, interposed the cylinder 50 and a fluid source 64, receives aninput signal such as engine speed or compressor discharge pressure.designated by arrows N and CDP, respectively. In response to the inputsignal, the control unit modulates the flow of fluid from the supplysource to the hydraulic cylinder 50 by way of conduits 66 and 68,communicating respectively with internal chambers 70 and 72 locatedwithin the cylinder 50.

Compressor performance may be easily measured by sensing one of severaloperating characteristics such as rotor speed or compressor dischargepressure. As best shown in H0. 2, the control unit 62 uses an electricalsignal output from a speed sensor or pressure transducer, not shown, tomodulate a valve supplying fluid to the hydraulic cylinder 50. Duringnormal operation at the optimum design condition, when directionalcontrol of the inlet flow is not required, the guide vanes 34 are fullyretracted into the housing 16. The control unit 62 supplies pressurizedfluid to the chamber 70 of the cylinder 50 while simultaneouslyevacuating fluid from the chamber 72 to force the piston 56 to itsextreme right position. This action produces a clock-wise rotation ofthe ring gear 42, thereby rotating the pinion gear 40 in a clock-wisedirection. Clock-wise rotary movement of the pinion gears 40, eachoperatively engaging a gear rack 36, produces a concurrent radiallyoutward retracting of the guide vanes 34. In this operating mode, thevanes 34 present no obstruction or blockage to the inlet air flow.

During compressor 10 operation at slightly less than the optimumcondition, directional control of the inlet flow of the rotor tip 22 isdesirable. As shown in the vector diagram of FIG. 6, the relative inletflow angle Beta can be reduced to a more nearly normal value byinsertion of a guide vane 34 into the inlet passage 32. Accordingly, thecontrol unit 62, sensing an operating condition somewhat less than theoptimum design condition, simultaneously relieves a measured amount offluid from the chamber 70 and adds a like amount of fluid to chamber 72.Transposition of fluid from the chamber 70 to chamber 72 forces thepiston 56 partially to the left, producing a correspondingcounterclockwise rotation of the ring gear 42 and the pinion gears 40.This motion produces a concurrent radially inward movement of the guidevanes 34 partially into the inlet passage 32 as determined by thecontrol unit 62. Consequently, the relative inlet flow angle Beta isreduced to an acceptable value, thereby reducing unwanted losses andincreasing compressor performance. Also, since the guide vanes 34 areinserted to influence only the inlet flow at the tip 22 portions,undesirable blockage of the inlet flow at the hub 24 is avoided.

When the compressor 10 is required to operate at other than the optimumdesign condition, the abovedescribed operation for partial vane assemblyextension is continued until the vanes 34 are fully projected into theinlet passage 32. The control unit 62 supplies fluid to the cavity 72and relieves the fluid contained in cavity 70 to urge the piston 56leftwardly. This action produces counter-clockwise rotation of the ringgear 42 and pinion gears 40, resulting in concurrent extension of theguide vanes 34 into the inlet passage 32.

What is claimed is:

1. In a compressor having a housing, a bladed rotor rotatably associatedwith the housing, and means defining an annular fluid inlet passageleading into the blades of said rotor and through which said fluidpasses to said rotor blades. the improvement which comprises meansselectively positionable in the annular fluid inlet passage to redirecta portion ofthe fluid passing to said rotor blades through said annularfluid inlet passage and removable to a substantial degree from saidannular fluid inlet passage, wherein the selectively positionable meansare completely removable from said annular fluid inlet passage, andwherein said selectively positionable means comprise a plurality ofguide vanes reciprocally associated with .the housing and movable intothe annular fluid inlet passage and outwardly therefrom, and means forselectively so moving said guide vanes, wherein said means forselectively moving the guide vanes into the annular fluid inlet passageand outwardly therefrom comprise a plurality of rack members, each rackmember having a guide vane fixed thereto and extending inwardlytherefrom, a plurality of pinion gears, each pinion gear being rotatablymounted to the housing and having the teeth thereof in engagement withthe teeth of a rack member, and a ring gear rotatably mounted to thehousing, each pinion gear having the teeth thereof in engagement withthe teeth of the ring gear, so that rotation of the ring gear relativeto the housing in one direction rotates the pinion gears to move therack members and guide vanes attached thereto inwardly of the annularfluid inlet passage, and rotation of the ring gear relative to thehousing in the other direction rotates the pinion gears to move the rackmembers and guide vanes attached thereto outwardly of the annular fluidinlet passage.

2. The apparatus of claim 1 and further comprising automatic sensing andcontrol means for rotating said ring gear relative to said housing inresponse to variations in selected compressor operating characteristics.3. A compressor comprising: a housing; a bladed rotor rotatablyassociated with the housing, rotatable about its axis and having bladeseach defining a tip portion and a hub portion; said housing defining anannular fluid inlet passage leading into the blades of the rotor andthrough which said fluid passes to said rotor blades; a plurality ofguide vanes reciprocally associ- 6 ated with the housing and movableinto the annular fluid inlet passage toward the axis of rotation of therotor, and outwardly therefrom to be completely removed from the annularfluid inlet passage, whereby, upon initial movement of the guide vanesinto the annular fluid inlet passage, such guide vanes are positioned toredirect a portion of the fluid passing to the tip portions of the rotorblades through the annular fluid inlet passage; and, means forselectively so moving said guide vanes, and wherein said means forselectively moving the guide vanes into the annular fluid inlet passageand outwardly therefrom comprise a plurality of rack members, each rackmember having a guide vane fixed thereto and extending inwardlytherefrom toward the axis of rotation of the rotor, a plurality ofpinion gears, each pinion gear being rotatably mounted to the housingand having the teeth thereof in engagement with the teeth of a rackmember, and a ring gear rotatably mounted to the housing, each piniongear having the teeth thereof in engagement with the teeth of the ringgear so that rotation of the ring gear relative to the housing in onedirection rotates the pinion gears to move the rack members and guidevanes attached thereto inwardly of the annular fluid inlet passage, androtation of the ring gear relative to the housing in the other directionrotates the pinion gears to move the rack members and guide vanesattached thereto outwardly of the annular fluid inlet passage.

4. The compressor according to claim 3 wherein the guide vanes aremovable toward the axis of rotation of the rotor to an extent sufficientto redirect a portion of the fluid passing to the hub portions of therotor blades through the annular fluid inlet passage.

5. The compressor of claim 4 and further comprising automatic sensingand control means for rotating said ring gear relative to said housingin response to variations in selected compressor operatingcharacteristics.

1. In a compressor having a housing, a bladed rotor rotatably associatedwith the housing, and means defining an annular fluid inlet passageleading into the blades of said rotor and through which said fluidpasses to said rotor blades, the improvement which comprises meansselectively positionable in the annular fluid inlet passage to redirecta portion of the fluid passing to said rotor blades through said annularfluid inlet passage and removable to a substantial degree from saidannular fluid inlet passage, wherein the selectively positionable meansare completely removable from said annular fluid inlet passage, andwherein said selectively positionable means comprise a plurality ofguide vanes reciprocally associated with the housing and movable intothe annular fluid inlet passage and outwardly therefrom, and means forselectively so moving said guide vanes, wherein said means forselectively moving the guide vanes into the annular fluid inlet passageand outwardly therefrom comprise a plurality of rack members, each rackmember having a guide vane fixed thereto and extending inwardlytherefrom, a plurality of pinion gears, each pinion gear being rotatablymounted to the housing and having the teeth thereof in engagement withthe teeth of a rack member, and a ring gear rotatably mounted to thehousing, each pinion gear having the teeth thereof in engagement withthe teeth of the ring gear, so that rotation of the ring gear relativeto the housing in one direction rotates the pinion gears to move therack members and guide vanes attached thereto inwardly of the annularfluid inlet passage, and rotation of the ring gear relative to thehousing in the other direction rotates the pinion gears to move the rackmembers and guide vanes attached thereto outwardly of the annular fluidinlet passage.
 2. The apparatus of claim 1 and further comprisingautomatic sensing and control means for rotating said ring gear relativeto said housing in response to variations in selected compressoroperating characteristics.
 3. A compressor comprising: a housing; abladed rotor rotatably associated with the housing, rotatable about itsaxis and having blades each defining a tip portion and a hub portion;said housing defining an annular fluid inlet passage leading into theblades of the rotor and through which said fluid passes to said rotorblades; a plurality of guide vanes reciprocally associated with thehousing and movable into the annular fluid inlet passage toward the axisof rotation of the rotor, and outwardly therefrom to be completelyremoved from the annular fluid inlet passage, whereby, upon initialmovement of the guide vanes into the annular fluid inlet passage, suchguide vanes are positioned to redirect a portion of the fluid passing tothe tip portions of the rotor blades through the annular fluid inletpassage; and, means for selectively so moving said guide vanes, andwherein said means for selectively moving the guide vanes into theannular fluid inlet passage and outwardly therefrom comprise a pluralityof rack members, each rack member having a guide vane fixed thereto andextending inwardly therefrom toward the axis of rotation of the rotor, aplurality of pinion gears, each pinion gear being rotatably mounted tothe housing and having the teeth thereof in engagement with the teeth ofa rack member, and a ring gear rotatably mounted to the housing, eachpinion gear having the teeth thereof in engagement with the teeth of thering gear so that rotation of the ring gear relative to the housing inone direction rotates the pinion gears to move the rack members andguide vanes attached thereto inwardly of the annular fluid inletpassage, and rotation of the ring gear relative to the housing in theother direction rotates the pinion gears to move the rack members andguide vanes attached thereto outwardly of the annular fluid inletpassage.
 4. The compressor according to claim 3 wherein the guide vanesare movable toward the axis of rotation of the rotor to an extentsufficient to redirect a portion of the fluid passing to the hubportions of the rotor blades through the annular fluid inlet passage. 5.The compressor of claim 4 and further comprising automatic sensing andcontrol means for rotating said ring gear relative to said housing inresponse to variations in selected compressor operating characteristics.